Molly

The mental institution where Molly has lived since childhood must close due to budget cuts. Buck is compelled to take responsibility for Molly, marking the first major shift in their estranged relationship. This sets the stage for Buck to become Molly's caregiver, despite their distant history.

Buck brings Molly to his advertising job after daycare proves unsuccessful. Molly barges into a meeting at the agency, naked, causing a scene and forcing Buck to intervene. The incident reveals how unprepared Buck is to manage Molly's needs within his high-powered, bachelor lifestyle.

Buck's assistant agrees to care for Molly while Buck tries to salvage his career. Molly slips away and ends up playing by a fountain, which contributes to Buck being fired from the agency. The upheaval leaves Buck with little support and pushes deeper into Molly's world.

Buck invites Sam from the institution to visit and help assess Molly's options. Sam recommends testing Molly for eligibility in a program at Buck's workplace that could help her connect with the wider world. This introduces the possibility of a formal path forward for Molly.

Dr. Susan Brookes, Molly's neurologist, proposes implanting genetically modified brain cells as an experimental therapy. Buck hesitates at first but ultimately agrees to proceed, hoping for a dramatic improvement in Molly's functioning. The decision marks a turning point toward medical intervention.

Soon after the surgery, Molly suffers a seizure, and Buck is visibly distressed by the risk of losing her. Dr. Brookes recommends a second attempt, but Buck refuses to pursue another procedure for now. The setback challenges both their hopes for a cure.

Several days later, Buck creates a list of simple learning goals tailored to Molly's abilities. He believes that clear, achievable steps could help Molly progress and feel more connected to the world. The plan represents Buck's growing investment in Molly's development.

Molly wakes up able to perform many tasks on Buck's list and begins speaking more fluidly. She interacts more readily with others, signaling a dramatic improvement. Buck becomes enthusiastic, and their social world starts to open up again.

Buck starts taking Molly to social events, including a production of Romeo and Juliet, a baseball game, and fancy dinners. Molly's increased engagement shows the potential of her renewed abilities, even as the gains feel fragile. The world outside starts to appear accessible again for them both.

After several hopeful months, Molly's brain begins to reject the transplanted cells and she regresses toward her earlier state. The loss hits hard for both Molly and Buck, who must confront the reality that the cure was not permanent. The couple faces a sobering new normal.

Buck and Molly must accept the regression and decide how to move forward together. Buck resolves to stay in Molly's life and support her as she is, rather than trying to force a cure. Their bond deepens through this unflinching vow.

In the final scene, Buck creates a room for Molly at his home that mirrors the room she had at the institution. He accepts Molly's autism and commits to remaining by her side for the rest of their lives. The room stands as a physical symbol of their lasting bond.